[NSRCA-discussion] Reducing the odds... - Now Cooling
Michael Wickizer
mwickizer at msn.com
Tue Mar 28 10:47:41 AKST 2006
Another good jurist overlooked...was it your stance on the death penalty or
perhaps your response to preferred methods of execution?
>From: "Earl Haury" <ehaury at houston.rr.com>
>Reply-To: NSRCA Mailing List <nsrca-discussion at lists.nsrca.org>
>To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
>Subject: Re: [NSRCA-discussion] Reducing the odds... - Now Cooling
>Date: Tue, 28 Mar 2006 13:12:28 -0600
>
>
>The foam cup trick works in some airplanes - fine in my E-Partner. Others,
>like the Abbra, present some problems with motor cooling. It's not easy to
>determine airflow into / inside the fuse - I played with smoke a bit to
>observe flows, but with limited success. As Dean points out - high pressure
>air in contact with the item to be cooled is the way to go. The foam
>"filler" is an easy way to achieve this - any air entering the ducts must
>flow over the motor, there's no other route.
>
>An added function of the foam is a low weight way to strengthen the fuse
>nose, some designs have little strength forward the normal firewall
>location. Of course this is where we need to mount the motor. The foam also
>reduces gear noise.
>
>Hopefully there're a couple of pics attached of the Abbra installation. The
>large hole in the bottom of the foam aligns with a baffle in the chin. Note
>also that the Comp motor is longer than the regular C50, so it protrudes
>from the rear mount (which actually forces some of the air through the
>spiral fins on the motor).
>
>Earl
>
>
>----- Original Message ----- From: "Michael Wickizer" <mwickizer at msn.com>
>To: <nsrca-discussion at lists.nsrca.org>
>Sent: Tuesday, March 28, 2006 9:54 AM
>Subject: Re: [NSRCA-discussion] Reducing the odds...
>
>
>>Nat:
>>
>>Not nearly as sexy or professional as Earl's solution, but I know somebody
>>that has used styrafoam coffee cups cut to size and glued in with CA.
>>Proved to be very effective and a quick install.
>>
>>Mike
>>
>>
>>>From: "Nat Penton" <natpenton at centurytel.net>
>>>Reply-To: NSRCA Mailing List <nsrca-discussion at lists.nsrca.org>
>>>To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
>>>Subject: Re: [NSRCA-discussion] Reducing the odds...
>>>Date: Mon, 27 Mar 2006 17:08:27 -0600
>>>
>>>Earl
>>>Can you provide more detail on the ducts ? Nat
>>>
>>>----- Original Message -----
>>>From: "Earl Haury" <ehaury at houston.rr.com>
>>>To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
>>>Sent: Monday, March 27, 2006 4:07 PM
>>>Subject: Re: [NSRCA-discussion] Reducing the odds...
>>>
>>>
>>> > Jim
>>> >
>>> > I've used the datalogger to monitor in-flight performance quite a bit.
>>> > Typically, during a P-07 flight the low voltage stays above 35v
>>> > (typically
>>> > <65A max) and power consumption is in the range of 3000 to 3400 mAh
>>> > (depending on wind) for an eight minute flight. I've set the ESC min
>>>volts
>>> > /
>>> > cell to 3.0v, but 3.3 would work. These numbers are similar with APC
>>> > 20x15,
>>> > 21x14, and 21x13W E props - Hacker C50XL-14 motor.
>>> >
>>> > Be observant of motor heating in the Abbra, I saw some pretty high
>>>numbers
>>> > with "typical" baffles. Filled the nose with foam (wing core type),
>>>bored
>>> > a
>>> > "tunnel" for the motor, and hot wired ducts. Motor stays very cool
>>>now.
>>> >
>>> > Earl
>>> >
>>> >
>>> >
>>> >
>>> > ----- Original Message -----
>>> > From: "J.Oddino" <joddino at socal.rr.com>
>>> > To: <chad at f3acanada.org>; "NSRCA Mailing List"
>>> > <nsrca-discussion at lists.nsrca.org>
>>> > Sent: Monday, March 27, 2006 1:16 PM
>>> > Subject: Re: [NSRCA-discussion] Reducing the odds...
>>> >
>>> >
>>> >> Hi Chad,
>>> >>
>>> >> I'm about to launch my first electric pattern plane and I'd like to
>>> >> get
>>> >> your
>>> >> opinion on my logic for setting the cutoff voltage. First of all I'd
>>> >> prefer
>>> >> that I'd never let any cell get below 3.3 volts per cell. However,
>>> >> I'd
>>> >> also
>>> >> prefer that the motor never stopped. My plan is to get to know the
>>> >> battery
>>> >> voltage vs. flight profile to accomplish both. I will set the cutoff
>>> >> voltage very low so it will never cut the motor. I will telemeter
>>>the
>>> >> voltage and current and keep track of the mAh consumed. If I see the
>>> >> voltage getting too low (<33V)under max load or use more than 80% of
>>>the
>>> >> capacity I will land. If I can't get through the pattern I'll >>
>>>probably
>>> >> need
>>> >> to go to a smaller prop. Once I am confident that the profile is
>>> >> consistent
>>> >> I can remove the TM system. What do you think?
>>> >>
>>> >> Jim O
>>> >>
>>> >> ----- Original Message -----
>>> >> From: "Chad Northeast" <chad at f3acanada.org>
>>> >> To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
>>> >> Sent: Sunday, March 26, 2006 10:45 AM
>>> >> Subject: Re: [NSRCA-discussion] Reducing the odds...
>>> >>
>>> >>
>>> >>> Hi Eric,
>>> >>>
>>> >>> Regardless of cutoff, its the resting voltage that is of paramount
>>> >>> importance for good pack life. A 1C discharge with a 3V/cell cutoff
>>> >>> will leave you with a very low resting voltage, as compared to a 15C
>>> >>> discharge with the same cutoff. Recently there has been a number of
>>> >>> discussions about increasing safe cutoff values as the C rates go up
>>> >>> since most of the current packs hold voltage so well up until then
>>> >>> end
>>> >>> when they simply dump everything they have....so 3 v/cell now equals
>>>to
>>> >>> a much deeper discharge than in the past.
>>> >>>
>>> >>> Then there is the problem that the ESC is only seeing average pack
>>> >>> voltage and not cell voltage...so its entirely possible while under
>>> >>> discharge to have a pair of cells at 3.2v (6.4 total) and the third
>>> >>> at
>>> >>> 9-6.4....or 2.6V, and now your ESC will cut properly...but that one
>>>cell
>>> >>> is being damaged.
>>> >>>
>>> >>> If you run a bit higher cutoff (3.1-3.2) and fly so that your open
>>> >>> circuit resting voltage is 3.75-3.8 you will have very happy
>>>batteries.
>>> >>>
>>> >>> I agree...there is not enough of this information available without
>>>a
>>> >>> lot of online reading. There is a lot of this on RC >>>
>>>Groups...although
>>> >>> it can take a significant amount of time to wade through the BS and
>>> >>> gather what is useful.
>>> >>>
>>> >>> Chad
>>> >>>
>>> >>> Grow Pattern wrote:
>>> >>>
>>> >>> >Chad,
>>> >>> > The speed controller cuts out at 9V. It actually drops to
>>> >>> > about
>>> >>> >8.3V under load and then settles back to 9.0V after the motor cuts.
>>> >>> >
>>> >>> >You know it's not so much that I am reporting what I personally do
>>> >>> >as
>>> >> much
>>> >>> >more like I am stating what the system does.
>>> >>> >
>>> >>> >The voltage cut-off end-user value options on the speed controller
>>>are
>>> >>> >selectable but still have fixed values. A three-cell pack has to
>>>use
>>> >>> >the
>>> >>> >9.0V option. I used my in-line meter to monitor and measure these
>>> >> results.
>>> >>> >
>>> >>> >Once again we are back to the instructions verses acquired >>>
>>> >knowledge!
>>> >>> >
>>> >>> >Regards,
>>> >>> >
>>> >>> >Eric.
>>> >>> >
>>> >>> >
>>> >>> >----- Original Message -----
>>> >>> >From: "Chad Northeast" <chad at f3acanada.org>
>>> >>> >To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
>>> >>> >Sent: Sunday, March 26, 2006 10:30 AM
>>> >>> >Subject: Re: [NSRCA-discussion] Reducing the odds...
>>> >>> >
>>> >>> >
>>> >>> >
>>> >>> >
>>> >>> >>>I now believe that I had a bad cell on the one that blew-up.
>>> >>> >>>
>>> >>> >>>
>>> >>> >>If you were discharging to 3 v/cell as I read it from your data
>>> >>> >>then
>>> >>> >>its
>>> >>> >>not surprising that you would have bad cells....a 3v/cell resting
>>> >>> >>would
>>> >>> >>indicate that you are discharging much below that under load.
>>> >>> >>
>>> >>> >>shoot for 3.7-3.8 v/cell resting (5-10 minutes) after the flight
>>> >>> >>and
>>> >>> >>your batteries will be much happier, and stay in balance all by
>>> >>> >>themselves for the most part.
>>> >>> >>
>>> >>> >>Chad
>>> >>> >>
>>> >>> >>
>>> >>> >>Grow Pattern wrote:
>>> >>> >>
>>> >>> >>
>>> >>> >>
>>> >>> >>>First of all thanks for all of the suggestions and advice from
>>>the
>>> >>> >>>list
>>> >>> >>>surrounding the charging of my Lipo's.
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>I have been messing with the big Lipo's since before Jason flew
>>> >>> >>>his
>>> >> most
>>> >>> >>>notable entry at the world's four years ago. This was my first
>>> >>> >>>catastrophic
>>> >>> >>>failure of a battery pack. I have spent around $7000 on electrics
>>>in
>>> >> that
>>> >>> >>>period of time and have closely monitored their technical
>>> >>> >>>development.
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>Right now I am working on sport type or sport level electrics.
>>>Not
>>> >>> >>>the
>>> >>> >>>foamy
>>> >>> >>>type or super light type of models, but the alternatives to 40
>>>sized
>>> >> glow
>>> >>> >>>motor powered models.
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>I particularly like the HIMAX offerings where they sell a motor,
>>>a
>>> >> motor
>>> >>> >>>mount, a matching speed controller and a prop all in one box.
>>>This
>>> >> saves a
>>> >>> >>>lot of guessing and previous trial and error on the part of the
>>> >>> >>>buyer.
>>> >> You
>>> >>> >>>are left with the choice of what battery pack and what plane to
>>> >>> >>>put
>>> >>> >>>it
>>> >> in.
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>Which brings us back to the exploding Thunderpower 4400 pack. I
>>> >>> >>>had
>>> >> been
>>> >>> >>>using my Astroflight 109 chargers with great success. I have 4 of
>>> >>> >>>them.
>>> >>> >>>This
>>> >>> >>>was before the little add-on balancers were available. They >>>
>>> >>>charged
>>>a
>>> >>> >>>bunch
>>> >>> >>>of different packs up to and including the big 4S3P packs with no
>>> >> problems
>>> >>> >>>etc. I am familiar with their warning etc. In particular, it >>>
>>> >>>states
>>> >> that
>>> >>> >>>it
>>> >>> >>>is not recommenced to charge a fully charged pack, (note: not
>>> >> forbidden).
>>> >>> >>>It
>>> >>> >>>further states that the charger will shut down the charge after
>>>about
>>> >>> >>>4
>>> >>> >>>minutes if you actually try and do this.
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>Now we get to the 3S pack in question. I was not satisfied with
>>> >>> >>>the
>>> >>> >>>knowledge of what happened and the comfort of how to prevent it
>>> >> happening
>>> >>> >>>again. I did not have another pack, or at least I was not going
>>>to
>>> >>> >>>risk
>>> >> an
>>> >>> >>>old friend's second and last pack. I did a couple of things.
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>I measured the each cell of my 3600 mAh Tanic's using the voltage
>>> >>> >>>taps
>>> >>> >>>that
>>> >>> >>>are part of the assembled pack.
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>CELL UP CELL DOWN
>>> >>> >>>
>>> >>> >>>I 4.18 3.01
>>> >>> >>>
>>> >>> >>>II 4.18 3.00
>>> >>> >>>
>>> >>> >>>III 4.19 3.01
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>Charging the pack when at 9.2V gave-
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>CELL UP
>>> >>> >>>
>>> >>> >>>I 4.18
>>> >>> >>>
>>> >>> >>>II 4.19
>>> >>> >>>
>>> >>> >>>III 4.18
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>Charging the pack when fully charged caused the charged to read
>>>it
>>>as
>>> >>> >>>3
>>> >>> >>>cells. It went through the 3 minute determination pause. Charged
>>>for
>>> >>> >>>about
>>> >>> >>>a minute and said "I'm done!" did this with two different 3600
>>>mAh
>>> >> packs.
>>> >>> >>>The charger did what it said it would do.
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>Then just as an FYI, I flew the model with both packs wired in
>>> >> parallel.
>>> >>> >>>One
>>> >>> >>>pack was giving me 5 minutes of flight at full throttle. I needed
>>> >>> >>>more
>>> >>> >>>air-time on the sport plane. (World models Sky Raider). I now had
>>>10
>>> >>> >>>minutes
>>> >>> >>>plus and the flight did not run out of steam.
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>The two packs were fully charged and the plane flown for about
>>>seven
>>> >>> >>>minutes.
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>This created a 3S2P pack. The readings were very encouraging.
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>PACK-A
>>> >>> >>>
>>> >>> >>>CELL UP CELL PARTIALLY DOWN
>>> >>> >>>
>>> >>> >>>I 4.18 3.68
>>> >>> >>>
>>> >>> >>>II 4.18 3.68
>>> >>> >>>
>>> >>> >>>III 4.17 3.67
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>PACK-B
>>> >>> >>>
>>> >>> >>>CELL UP CELL PARTIALLY DOWN
>>> >>> >>>
>>> >>> >>>I 4.18 3.68
>>> >>> >>>
>>> >>> >>>II 4.19 3.68
>>> >>> >>>
>>> >>> >>>III 4.18 3.67
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>The cells were discharging and charging nice and equally.
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>My charging practices have been upgraded to.
>>> >>> >>>
>>> >>> >>>1. Test voltage of each cell before each charge.
>>> >>> >>>
>>> >>> >>>2. Monitor the charge initiation.
>>> >>> >>>
>>> >>> >>>3. Place pack on 1/2" metal plate on table outside of van. (Deep
>>> >>> >>>Cycle
>>> >>> >>>marine 12V is in back of van).
>>> >>> >>>
>>> >>> >>>4. Check reading periodically.
>>> >>> >>>
>>> >>> >>>5. Test voltage of each cell after each charge.
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>I now believe that I had a bad cell on the one that blew-up. I
>>> >>> >>>also
>>> >> would
>>> >>> >>>not charge the TP pack without the after-market device. In fact I
>>>now
>>> >> do
>>> >>> >>>anything to reduce the odds of another accident.
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>Just looking at the display on the 109 charger tells you a lot.
>>> >>> >>>The
>>> >> number
>>> >>> >>>cells, the voltage during initialization and during charge, must
>>> >>> >>>be
>>> >>> >>>correct,
>>> >>> >>>or at least in range. Putting the pack in a fire safe place is
>>> >> paramount.
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>Regards,
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>Eric.
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>_______________________________________________
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>>> >>> >>>NSRCA-discussion at lists.nsrca.org
>>> >>> >>>http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
>>> >>> >>>
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>>> >>> >>
>>> >>> >>
>>> >>> >
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